The present invention is directed to semiconductor devices and electronic circuit boards. More particularly, the present invention is directed to added impedance in semiconductor devices and electronic circuit boards.
Current designs of semiconductor circuits require certain impedances between the power plane and the ground plane. These impedances are generally placed on the die or on the substrate of the circuitry. For example, decoupling capacitors are typically placed in circuits, between the power plane and ground plane, to stabilize any undue voltage fluctuations in the traces. Similarly, resistances may also be used at various locations in circuits to add impedance.
FIG. 1 illustrates a semiconductor circuit with added impedance using known methods. Between a power plane 10 and ground 16, a surface mount capacitor 12 and a surface mount resistor 14 is added. Capacitor 12 and resistor 14 are usually hand-soldered on the substrate requiring additional resources. They also occupy precious real estate on the substrate. In addition, due to the considerable length of the trace (L) between power plane 10 and ground 16, the trace can act as an antenna for electromagnetic interference (xe2x80x9cEMIxe2x80x9d) and other high frequency noises.
Based on the foregoing, there is a need for an improved method and apparatus for adding impedance between planes in a semiconductor circuit.
One embodiment of the present invention is a circuit board that includes two planes. A via spans the planes, and an impedance component is placed in the via. The impedance component is coupled to both of the planes.